Ian McKellen as Sherlock Holmes

Laura Linney as Mrs. Munro

Milo Parker as Roger

Hiroyuki Sanada as Tamiki Umezaki

Roger Allam as Dr. Barrie

Frances de la Tour as Madame Schirmer

Hattie Morahan as Ann Kelmot

Phil Davis as Inspector Gilbert

Patrick Kennedy as Thomas Kelmot

John Sessions as Mycroft Holmes

Frances Barber as Matinee "Madame Schirmer"

Charles Maddox as Oswald

Takako Akashi as Maya Umezaki

Zak Shukor as Masuo Umezaki

Michael Culkin as Bank Manager

David Foxxe as Chemist

Oliver Devoti as Ticket Agent

Mike Burnside as Ann's Solicitor

Nicholas Rowe as Matinee "Sherlock Holmes"

Sam Coulson as Matinee "Thomas Kelmot"

Hermione Corfield as Matinee "Ann Kelmot"

Kit Connor as Boy

Zoe Rainey as Boy's Mother

Eileen Davies as Lady on Platform

Colin Starkey as Dr. John Watson

Sarah Crowden as Mrs. Hudson

Elizabeth Jane Cassidy as Waitress (uncredited)

John Carr as Patron in Cinema (uncredited)

Johnny Otto as Army Officer (uncredited)